Tracking display for aircraft



July 5, 1960 M. E. CAMPBELL ATTORNEY July 5, 1960 M. E. CAMPBELL 2,943,824

j TRACKING DISPLAY FOR AIRCRAFT MARK E. CAMPBELL ATTORNEY M. E. CAMPBELL 2,943,824

TRACKING DISPLAY FCR AIRCRAFT 3 Sheets-Sheet 3 INVENTCR.

ATTORNEY July 5, 1960 Filed oct. 18, 1955 MARK E. CAMPBELL Mark E. campbeitwhiffiea Calif., gegner to North j American Aviation, Inc.

Enea oct. 1s, 195s, ser. No. `541,151 1o claims. (cl. 244-77) This invention relates to a correction display device and particularly to an improved tracking display for aircraft.

Present interceptor aircraft are provided with a re and flight control computer, an autopilot and associated circuitry which is normally capable of accurately guiding the interceptor to a preselected position relative to an enemy target. `Upon arrival at this. preselected position, the interceptor launches its rockets or res its*` guns .for the purpose of destroying the enemy aircraft. The intercepto'r aircraft is further provided with a control device, called a formation stick, which can be utilized to guide` the interceptor aircraft in manual operation. The formation stick can be displaced about two axes, known as the pitch and yaw axes, and provides the pilot with a 'convenient means for maneuvering the interceptor through the medium of hte autopilot. When the fo'rmation stick is displaced in pitch, the autopilot causes the interceptor to pitch at a rate determined by the magnitude of the stick displacement. When the formation stick is displaced in yaw,`the autopilot causes the interceptor to roll into a coordinated turn in which the yaw rate is determined by the amount of stick displacement.

" The tire control computer, utilized in the interceptor,

converts inputs from a conventional altimeter, radar, machmeter, vertical gyro` and` rate gyros into electrical signals, which are predetermined functions of the 1n- .stantaneous pitch and yaw angles of error, 2z and 2y.

The total aiming error angle, E, is defined as the angle between the instantaneous heading of the intercepto'r aircraft and the computed heading of the interceptor aircraft necessary to position the interceptor at the above-mentioned preselected position, or launching point, relative to the target. The total aiming error angle is the vector sum of the pitch aiming error angle and the yaw aiming error angle. When the interceptor is operating in the automatic mode, the outputs of the fire control computer are coupled directly to the autopilot and produce in the to the more accurate automatic mode when the firing time is a few seconds away if conditions are favorable. In the manual mode of operation of the autopilot, the pilot is guided by a display o'n an oscilloscope whichrindicates the instantaneous total aiming error angle of the interceptor, as Well as its pitch and yaw components.

The manual or pilot-link mode has several advantages as an independent or alternate lire control mode. When utilized during radar lock-on, the sudden transients due to the direct coupling of the fire control computer to the autopilot following radar lock-on are avoided. Further, the pilot-link mode places the pilot in the system a 12,943,824 Patented July 5, 1960 2 in such a Way that he is lfree to exercise judgment and prediction. `He is in a position Vto lead the error signalsA o'n the basis of experience and training to anticipate the change in interceptor response required bytarget ma# neuvers in away which augments the automatic prediction of the re control computer. t Also, in steady turns the pilot can bring to zero the aiming error angle signals as an automatic integrator would do but without the disadvantage of holdoverof an integrated error signal during the 4transient following the steady turn. Further, when the radar glint noise becomes severe, the pilot using -the pilot-link mode acts as an adjustable filter, exercising judgment in his mental averaging of the displayed error signals.

As has been previously noted, the pilot is provided with a display on the oscilloscope which, by means of a dot displacement relative to aircraft coordinates, gives him an accurate indication of the aiming error angles. When the pilot decides that corrective action is required to bring the aiming error angle to zero, he displaces the formation stick about its two' axes of motion. He must judge how far to move the stick `abouteach axis on the basis of guess, training or previous experience. His action on the stick is completed in a very short time, considerably before he notices any appreciable movement of the error do't on the oscilloscope in response to his action. In some cases, especially when the target is maneuvering violently, the response of the error dot to the displacement of the formation stick is completely obscured. Ordinarily, if the pilot moves the stick in a manner to generate the correct pitch, yaw and roll rates, the error dot begins to move'back towards center. Now the pilot must judge when to return the formation stick to zero so that the dot does not overshoot. The action of the stick relative to the dot displacement is dicult to judge.

It is therefore an object o'f this invention to provide an improved tracking display for aircraft useful for accurately maneuvering an aircraft relative to a target.

It is another object of this invention to provide an improved tracking display utilizing an oscilloscope which, in addition to displaying an indication of the aiming erro'r angle, also displays an immediate indication of the action by the pilot to compensate for said aiming error angle, so that it is unnecessary for the pilot to wait until the aircraft stabilizes inmotion or attitude to observe the attitude of his corrective action. It is a further object of this inventio'n to provide an improved correction display device for indicating the magnitude of a correctional factor utilized to compensate for errors in a condition indicating system.

It is another object ofthis invention to` provide an im proved tracking display for aircraft useful for accurately maneuvering an aircraft in relation to a target.

Other objects ofthis invention will become apparent from the `following description taken in connection with the accompanying drawings, in which t Fig. 1 is asimpliiied block diagram of the computerformation stick'autopilot combination utilizing a pre* ferred embodiment of this invention;

Fig. 2 is a vector diagram of a typical fire and flight control problem solved by the computer of Fig. l;

Fig. 3 is a block diagram of the servo loops utilized in the preferredV embodiment of this inventio'n shown in Fig. l;

Fig. 4 isa detailed block diagram of the tracking display circuit utilized in the embodiment of Fig. 1;

And Fig. 5 is a view of -a typical oscilloscope display on the plate of the oscilloscope of Fig. 4.

Referring now to Fig. l, a simplified block diagram of the computer-formation stick-autopilot combination utishown;l Fire and ight control computer 1 utilizes in- 3 puts `from conventional l-altimeter 2, radar 3, machmeter 4, vertical gyro V5 and rate gyros 6,to generate electric -signals which are predetermined functions of the instantaneous pitchaiming error angle 2z and the yaw aiming error;angle'2y. These electric signals-are utilizedlinthe automatic kmode ltoy generate inthe autopilotsignalswhich are .predetermined4 functions of a vdesiredjpitch rate Qc; yaw rate tpmland'roll rate es; ','I'he magnitudes' of lthese ratesignalsrrelative to theerrorangle signals are {preselected .to reduce the .computed` aiming 'error angles to rzero asxrapidly;as possible, taking into consideration theaerodynamic :characteristics of the .interceptor aircraft. ,As has been previously ypointed .out,"the total aiming error angle is deiinedffasfthe instantaneous angular errorin the Y heading :of the interceptor `compared tothe computed heading to the armament launching pointas shown in Fig. 2. The -total aiming error angle has two componenttparts, theipitch aiming error angle, lZwandfthe yaw aimingerror-anglaLEy. l

Computers have `been developed in the ;past ywhich generate the aforementioned aiming error angles utilizing such computed information as speed, heading and .altitude of theV interceptor; therangeybearing and the .rates ofchange Vof range and bearing of the target; andthe armament velocity. `Utilizing*principles well-known to those-skilled `in the art, these-computers `solve the vector diagram of Fig. `2 in .a manner to produce an indication of zthe total aiming error angle, #2. .The Vcomputer valso resolves this totalaimingierror Yangle'intozits components about ,the-'pitch' and yaw axes of the interceptor, includingtheeffect of roll. Autopilot-interceptor Sresponds to these error component signals rfrom computer `1 togenerate commanded .rate signalswhich actuate the'control surface servos of autopilot It` When-switch V'l is `in the automatic mode position. These aimingrerrorlangle signals are disconnected'from 'autopilot SWhen the manual modeis used. `v

As has been previously pointed Vout,factors such as violent maneuvering of the 'enemy .aircraft and :radar glint 'noises frequently make vit'desirable to switch'from the fully automatic actuation of the autopilot 8 to 'a manual operation. When Yswitch 7 is positioned for manual operation of autopilot'S, the Vsignals from lire and flight control computer 1, which Yiare proportional to the pitch and yaw aiming error angl, rcontinue tobe conveyed to oscilloscope l9, thereby providingja visual indication of the magnitude `of these error angles. The pilot can then generate desired correction signals .by moving vformation stick .10 to actuate 'autopilot 8 .in:a manner to reduce the aiming error angle to zero.

Referring now to Fig. .5,-a view of a typical oscilloscope display is shown. VFixed horizontal andvertical reference lines 11 and 12 oni thesurface 'of theloscilloscope'Iprovide visual Yindications of the yaw .and pitch axes, respectively, vof a graphic indication of the -total aiming error angle. Bya circuit to be ldescribed later, dot 513 ,is displacedifromithe intersection of vlines `11. and 112 by an'amount proportional to theraiming error anglei! The displacement ofdot 13 `along horizontal line-1:1 is made proportional `to the yaw aiming verror angle Ey, While the displacement valong Vverticallinev 12 is made proportional to the pitch-aiming-error angle EZ. Thus, when the pitch and yawairning error-angle signals are coupled from the computer to `thevertical and vhorizontal deection plates, respectivelyyof Aone gun rof oscilloscope 9 ofFig. 1, dot T13 is positioned in such a Way tha-t both error components are readily available to the pilot. Itis to be -noted that thereis-al fixed relationship between the actual value of the aiming -errorfin degrees andthe corresponding displacement of the error dot on the oscilloscope face. This relationship is-called the error dot gain, in degrees-of aiming error p er inch of dot displacement. Preferably,theerror'dot gain Iis the same with reference to each of 'the jreferenceaxes *ofV the oscilloscope presentation. An error .dot gain of from two to ve degrees lper inch is a typical value. The signs of the errorsignals are so arranged that the dotv represents the relative target position. In the manual mode the pilot ,utilizes the formation stick to maneuver nthe interceptor toward theY dot in order to bring the dot to the center of the oscillof scope.

lIt is to be noted that when the interceptor rolls, horizon reference line 14 on the oscilloscopechanges position accordingly, and e'rror ,dot 13 also moves, maintaining a relatively steady -relationship to the'hori'zon reference, assuming a constant total'aiming error. aiming error angle indicationshown in lFig,-5 can also be resolved into inertial horizontal and vertical aiming Y error angles 2y' randV 2z', referenced to the true horizontal and vertical axes as determined by conventional gyro` f mechanism utilized in manual operationof Vtheinterceptor is shown. lWhen pilot 15 moves stiehlt), autopilot-8 actuates the stabilizer, rudder and aileron "(not shown) of the interceptor in a direction determined '-bylthe dis-Y placement of stick 10. Theactuation of the stabilizer, rudderand aileron result inpitch, yaw and'rolLjrespectively, of the interceptor. These interceptormotions affect thepitch,` roll and yaw aiming error signals vgenerated by computer 1. "If the interceptor control surfaces have been movedin the correct direction, the 'aiming `error signals are reduced. This reduction is Iindicated on oscilloscope 9 by a movement of dot 13 toward reference lines lland 1270i? Fig. A5. A second factoraecting aiming error. angles is a deviation of the targetair'plane from its predicted course and speed. ,The 'i response of computer 1 to the target motions'is practically 4instaritaneous. it is to be noted, however, .that there is `an appreciable time lagbetween the movement of 'formation stick 10 by pilot 15 and the response of the interceptor. This time lag `makes it very diicultfor the pilot to'judge the magnitudeand length of time he should displacej'formation stick 10. `By providing a secondary servo `loop between the output of stick 10 and theV input to scope Y9, 'the display 'system contemplated by this 'invention provides arapid indication,` visually presented to the` pilot, of the effect of any. displacement of the formation stick. I Referringnow to VFig. 4, formation stick`1'0'is atwoaxis control andproduces two signals, oneV dependent on itsfore-and-aft (pitch) displacement and lone dependent on .its lateral (yaw) displacement. The stickfi'sreturn'ed to the center or null position by springs '(notgshovvn), which are preloaded'enough to facilitate' restoration when pressure-onthe stick lis removed. In the manualmode of operation 'the signal .Y responsive to :displacement of stick V10 about the pitch Vaxis of the stick is-coupledY into the pitchrate channel in place ofrthe pitch .aiminggerror signal from/computer land the signal responsive to;dis placement ofhformation Astick l10 about rthe hyaWfaXis. of the stick` is .coupled iutovthe yaw yand :roll vrrate channels in Vplace ofthe `yaw aiming error signal from computerl. Except forfdifferencesin relative signal levels, :thefoperation of autopilot-8 in `the .manualimode isnthe same as in the fully-:automatic mode. Y

"InFig. 4, 'a detailed `blockdia'gram of the electronic circuits of a preferred embodimentpf-this invention Lis shown. AsV previously pointed out, tire control computer 1 generates electric signalsproportional to pitchaiming error angle 2z and yaw aiming error angle-2y. When switch7 -is in the manual position as shown, the aiming error signals from the tire control computer are disconnected v*from 4autopilot 8. Autopilot-S now .receives Therefore, the

. l y 5 signals only from the'formation stick 10, and interprets them as commanded rate signals.

The laiming error signals from `fire control computer 1 l are continuouslyconveyed to the deflection plates of one gun of oscilloscope 21. Thus, pitch aiming' error signal 2z is coupled through amplifier 22 to the verticalr deflection plates of one gun of oscilloscope 21, and yaw aimingerror signal 2y is conveyed through amplier 23 to the horizontal deflection plates of the same gunof oscilloscope 21. In a manner similar to that previously describedwith respect to `Fig.,5, dot 2,4 on face of oscilloscope 21 is displaced from horizontal reference line 25 by an amount proportional to the pitch aiming error. Similarly, dot 24 is displaced from vertical reference line 26 by an amountwhich is proportional to the yaw aiming error.

The pilot (not shown), seeing that the interceptor is not headed on the correct course to reach the launching point, displaces formation stick 10 about its two axes of freedom. This displacement generates electric signals which are predetermined functions of the displacement predetermined function of the magnitude of the angular" rotation of formation stick 10 about the pitch axis and which has a polarity which is determined by the direction o f movement of formation stick 10 from a neutral or null position. `Similarly, movement of formation stick 10 to the left or right results in a D.C. voltageV on wiper 29 of potentiometer 30, which has a polarity dependent on the directionnof ,motion and a magnitude which is a predetermined function of the magnitude of the angular displacement of .stick 10 about the yaw axis.

`The signal from `formation stick 10, which is proportional to the displacement of the stick aboutV the pitch axis, is coupled through amplifier 31 to summing network 32 of autopilot S. The output `of amplifier 31 is `an electric signal which is proportional to a formation or commanded pitch rate, f, corresponding to magnitude of displacement of formation stick 10 about the pitch axis. This commanded pitch rate, f, is compared in summing network 32 to the instantaneous actual pitch rate, bg, of the interceptor as indicated by a signal from pitch rate gyro 33. For the same formation, or commanded, and actual pitch rates, tlf and g, respectively, the signals from amplifier 31 and pitch rate gyroscope 33 are designed to be equal and opposite. As long as the two input signals to summing network 32 are equal and opposite,\output signal 0e is zero. A change i-n one of` the input signals results in `a signal output, 0e, of summing network 32 proportional to the difference in input signals. This error pitch rate, 0e, is coupled to control surface servo34. Control surface servo 34, when actuated by a signal from summing network32, causes a movement of the stabilizer (not shown) o f the .interceptor. This results in a change in the pltch rate of the interceptor and a corresponding change in the output, g, of pitch rate gyro 33. When the instantaneous pitch rate, g, is equal to the formation or commanded pitch rate, f, the output of summing network 32 is reduced to zero and the stabilizers are maintained in their adjusted position until formation stick is again moved about itspitch axis. l p

The signal from formation stick 10, which is proportional to the displacement of the formation stick about the yaw axis, is coupled through amplifier 40 to summing network'41. The output of amplifier 40 is an electric signal which is proportional to the formation or commanded yaw rate, iff, corresponding to the magnitude Vof asiatici' the command displacement of formation stick l'tlaboiit the yaw axis; a erates an electrical signal which is proportional to the instantaneous actual yaw rate, lpg, of the interceptor. For the same formation or command signals and actual yaw ratesm/.ff and 112g, respectively, the signals from plier 40 and yaw rate gyroscope 42' are designed to `be equal and opposite. As long as the two input signals to summing network 41 are equal and opposite, output signal gb', is zero. A change in one of the input signals, such as results from a change of position of stick 10 about its yaw axis, unbalances network 41, causing a signal :pie to be coupled to control surface servo 43. The polarity and magnitude `of this signal are determined by the direction and magnitude of the unbalancing of network 4l. In response to the yaw rate error signal, ipe, control surface servo 43 adjusts the position of the rudder (not shown) Vof the interceptor. ceptorresponds tothis rudder change, the output of yaw rate gyro'42 also is changed, thereby re-establishing the balance between the inputs to summing network 41. The rudder is `then maintained in its new position until network 41 is again unbalanced.

The signal from formation stick 1t) resulting from displacement of the stick about its yaw axis is also coupled to the roll channel of autopilot 8 through lagged differentiator 44 and amplifier 45. Lagged dilferentiator 44 produces a signal approximately proportional to the rate of change of the formation stick position. The purpose of the actuation of the ailerons (not shown) by the roll channel of the autopilot is to produce a momentary roll rate in the proper direction to establish a coordinated turn; In addition to this initial signal, a sideslip angle signal is coupled into the roll channel through amplifier 46 and summing network 4'7. This signal is designed to actuate the ailerons in a manner to produce a roll ratel in such a direction as to reduce the sideslip angle to zero. The output of summing network 47 is therefore a signal, of, proportional to a desired roll rate of the interceptor. This signal is compared to the actual roll 4S is again `equal to the formation roll rate signal'q'bf,

signal pe reduces to zero and the ailerons are maintained in their new position until network 49 is again unbalanced The signals proportional to the displacement of formation stick lt) about the pitch and yaw axes are also coupled through amplifiers 51 and 52 to `the vertical and horizontal deflection plates, respectively, of a second gun of oscilloscope 21. A visual indication of the magnitude of movement of formation stick 10 aboutthese axes is thereby presented on the plate of oscilloscope 21. In order to readily differentiate between the indications on the plate of oscilloscope 21 resulting from the aiming error angle signals from tire control computer 1 and the signals resulting from the movement of formation stick 10, a variation in the pattern indicated onthe plate is incorporated into the oscilloscope circuitry. Thus, sine and cosine generator 53 is utilized to generate small sinusoidal signals which are coupled to the vertical and horizontal deflection plates of 4the second gun of oscilloscope 21. As a result of these signals, instead of.

a dot appearing on the plate of oscilloscope 21, the second gun generates small circle 54. The displacement of the center of this circle from the reference axes 25 and 26 is made proportional to the pitch and yaw rates generated by moving formation stick 10.

The desired pitch and yaw rate signals from move- Yaw` rate gyroscope 42 continuously gen-i As soon as the inter-l ment ofthe` formation stick are limited by the maximum stick displacement.V The roll rate obtainable isv dependent v of the gains in the various circuits. As an example, using an -error dot gain of two degrees per inch on the face of the oscilloscope 21, a skilled Ypilot canvreadily maintain circle 54 about dot 24 when full stick displacement causes circle 24 to move one inch in both directions and-,the corresponding pitch and yaw rates called for by Ysuch full stick displacement are ten degrees per second. A variation in the sensitivity of the system can readily b e obtained by varying the gain of amplifiers 51 and 5,2, lthe'reby'reducing or vincreasing the response of circle 54 in'pitchand yaw, respectively, for a given displacement of formation (stick It?.

v'It is the-purpose of the above-described display system to'enable the 'pilot' to immediately see the result of his displacement of formation stick l0. All the pilot need do yin order to reduce the aiming error signal to zero is to maintain circle 54 about dot 24. If this is done,

dot 24 normally progressively moves toward thecenterV of the oscilloscope. The speed at which dot 214 moves toward the center of the scope is determined by `the gain ofampliiers l VVand 52. -If amplifiers 51 and 52 have a low gain, dot 24 moves rapidly toward the center'of the oscilloscope for a given stick displacement. lf amplier's 51 4and 52 have a high gain, the same displacement 'of stick itl results in a large displacement of circle 54 and .dot 24x moves more slowly toward the center of the oscilloscope. This is due to the lower rates being generated by autopilot 8 for a given position of circle 54. The setting of amplifiers 5 1 and 52 is adjusted to correspond 'to the `skill and speed of response of the pilot in his actuation of formation stick lll. It is to be noted that as dot 24- moves toward the center of the scope, and as the pilot maintains circle 54 superimposed about dot 24, the correction signals conveyed 'to the autopilot `8 are progressively decreased, thereby greatly reducing the chances of overshooting the computed heading.

The improved display device is described above in connection with tracking aircraft. This invention is not limited to such use. The display device can be used in any condition indicating ysystem to immediately indicate to "the operator the magnitude of the 4rate of correction he is applying `to compensate for deviation V'of vthe condition from a desired state. v

Although this invention has been described and illu'strated in detail, it is' to be clearly yunderstood that the same is by way of illustration and example only and is not -to be taken by Vway of limitation, the spirit and scope of this invention being limited only by the terms ofthe appended claims.

I claim: 1. In a device for guiding an airplane, .the combination, with an autopilot arranged to guide said airplane in accordance with received command signals and a re control computer arrangedvto furnish computed command signalsto said autopilot to direct saidplane alongl a com- 3. improved tracking display for aircraft useful for accurately maneuvering an aircraft in 'relation to la target V,comprising computer means having' a signalV output proportional'to'theaiming error angle of said aircraft;

a formation stick in A,said aircraft; aircraft maneuveringl meansfresponsive to the displacement of said Aformation i stick ',c'ounec'ted to change at an adjustable rate the heading ofsaid aircraft, said`rate being determinedV by;

the magnitude of displacement of said Vformation stick;

signal generating means connected to producean output;

proportional to the displacementof said formation stick and means forcomparing the` outputs of said computer means and said signal generating means.

Y ,41A trackingfdisplay for aircraft as recited in ,claim in which said comparing means comprises an oscilloscope having separate visual outputs for each input'signaland means for individually subjecting saidoscilloscope tothe output`signals of said computer means and said signal generating means. r f '5. 'An improved tracking display foraircraft for accurately maneuvering an aircraft relative to va target comprising computer means having signal outputs proporsupplyy said manual command signals to said autopilot,

and means for displaying said manually supplied command lsignals simultaneously with computed comm-and signalsrfroms'aid re control computer, whereby a visual comparison of said manually commanded and said 'computed signals may be made.

2. A correction displaydevice as recited in claim ,1 in which said signal comparing means comprises an oscilloscope having separate visual outputs for said cornmand 'signals and for said computed signals, and means for individually Vsubjecting said oscilloscope'to the outputs 'of means for generating said computed signals and to the output of means llfor Computing said command signals.

tional to the aiming Y,error angles about two'per'pendicular axes; an oscilloscope having separate visual outputindications for input signal groups representing saidaiming error angler signals and Arepresenting Acommand signals;

vmeans:subjecting said oscilloscope Vto the signal outputs of said computer means in ya manner to produce a visual.

indication displaced frompreselected reference axes on the ,plate of said oscilloscope 4by amounts'respectively proportional to said'signal outputs vof said fcomputer means; aformation stick having degreesof freedom about each of two perpendicular axes;` command signal ygen'- erating means having outputsignals respectively proportional to the magnitude of displacement of said formation stick about each of said formation stick axes; means subjecting said oscilloscope to the signal outputs of said command signal generating means in a manner to produce arvisual indication displaced from preselected axes on the face of said oscilloscope byan amount respectively proportional to said signal outputs of said command signal generating means; and'aircraft maneuvering means responsive to the displacement of said formation stick and connected to change, atpreselected rates proportional to the displacement of said formation stick about said two vformation stick axes, the heading of said aircraft about vsaid two aiming error axes. a u

V6. An improved tracking display for aircraft useful for accurately maneuvering an aircraft in relation to `a target comprising means for producing error signals which are predetermined functions of the ferrors in aircraft pitch direction and aircraft yaw direction consistent with su'ccessful interception of said target, an oscilloscope responsive to said error signals forrdisplaying the magnitudes and directions of said pitch and yaw errors, aircraft maneuvering means connected vto changeat adjustable rates the .aircraft pitch directionV and aircraft yaw direction, signal generating means having .outputs Y which are predetermined functions of'the rates ofjchange of said pitch and yaw directions in response "to said aircraft maneuvering means, and means responsive to said rate signal vgenerating means for displaying onsaid oscillog j scope an indication of'said rates of change of pitch and yaw directions. l A

7. An improved tracking display for aircraft useful for accurately maneuvering an aircraft relativeto a target comprisingv4 computer fmeans for generating error signals which are predetermined functions of the aiming errors a two lpreselected perpendicular reference axes on the plate of said oscilloscope by amounts respectively proportional to `the pitch'and yaw aiming error signal outputsof said `computer means; a` formation stick having degrees of freedom about two perpendicular axes; aircraft maneu-V vering means responsive to the movement of said formation stick from a preselected null position in a manner to vary at preselected rates proportional to the magni` tude of the displacement of said formation stick, the attitude of said aircraft about pitch, yaw and roll axes, said -aircraft maneuvering means being responsive toy displacement of said formation .stick about Vone of said axes in a manner to produce a pitch rate of said aircraft and said aircraft maneuvering meansrbeing responsive to the displacement of said formation stick about the second of said axes in a manner to produce a yaw rate of said aircraft and a roll rate sufficient to produce a coordinated turn of said aircraft; command signal generating means having individual pitch and yaw rate output signals proportional to the displacements of said formation stick about each of said axes of freedom; and means subjecting said oscilloscope to said output signals from said command signal generating means in a manner to provide a visual indication on the plate of said oscilloscope which 4is displaced from said two perpendicular reference axes with said yaw rate output signal resulting in displacement of said visual indication from the same axis and in the same direction as the visual indication of the yaw aiming error signal and the pitch rate output signal resulting in displacement of said visual indication from the same axis and in the same direction as the visual indication of the pitch aiming error signal.

8. In a tracking display system for aircraft, means for generating an error signal indicative of the deviation of said aircraft from a predetermined heading, automatic aircraft maneuvering means for changing the heading of said aircraft at an adjustable rate, means responsive to manual control for producing a command signal which is a predetermined function of a desired rate of change of the heading of said aircraft, means for alternatively subjecting said aircraft maneuvering means tosaidv manual control command signal and said error signal, and means for Vcontinuously comparing said error signal with said command signal to'pro'vide a guide for the operator of said manual control means.

9. In a tracking display system for aircraft, means for generating an error signal indicative of the deviation of said aircraft from a predetermined heading, automatic aircraft maneuvering means for effecting a rate of change of heading of said aircraft in response to aninput signal supplied to said maneuvering means, means responsive to manual control for producing a command signal which is a predetermined function of a desired rate of change of the heading of said aircraft, and means for alternatively supplying said command signal and said error signal to said maneuvering means as the input signal thereto. Y

10. In combination with a lire control computer, an aircraft, and an automatic pilot adapted to operate in conjunction with said computer, means for presenting pitch and yaw aiming error signals' derived from said fire control computer, a manually operable for-mation stick adapted to supply command signals to said autopilot, and means forsimultaneously presenting manually commanded signals from said formation stick for comparison with said pitch and yaw aiming error signals, whereby the pilot may compare said manually inserted command signals with said pitch and yaw aiming error signals.

VReferences Cited in the le of this patent UNITED STATES PATENTS 2,463,529y Ferrill Mar. 8, 1949 2,613,352 Kellogg 2nd Oct. 7, 1952 2,644,941 Kellogg 2nd July 7, 1953 2,698,723 Y Kutzler Jan. 4, 1955 

